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Autosomal dominant Alport syndrome: molecular analysis of the COL4A4 gene and clinical outcome

2009; Oxford University Press; Volume: 24; Issue: 5 Linguagem: Inglês

10.1093/ndt/gfn681

1460-2385

Elena Marcocci, Vera Uliana, Mirella Bruttini, Rosangela Artuso, Margherita Silengo, Marlenka Zerial, Franco Bergesio, Antonio Amoroso, Silvana Savoldi, Marco Pennesi, Daniela Giachino, Giuseppe Rombolà, Giovanni B. Fogazzi, Maria Cristina Rosatelli, Ciro Dresch Martinhago, Mario Carmellini, Roberta Mancini, Giuseppina Di Costanzo, Ilaria Longo, Alessandra Renieri, Francesca Mari,

Renal and related cancers

Background. Alport syndrome is a clinically and genetically heterogeneous nephropathy characterized by glomerular basement membrane lesions often associated with hearing loss and ocular anomalies. While the X-linked and the autosomal recessive forms are well known, the autosomal dominant form is not well acknowledged. Methods. We have clinically investigated 38 patients with a diagnosis of autosomal dominant Alport syndrome belonging to eight different families. The analysis of the COL4A4 gene was performed by denaturing high performance liquid chromatography and automated DNA sequencing. Results. In our cohort of patients, only 24.3% (9/37) reached end-stage renal disease, at the mean age of 51.2 years. Four patients had hearing loss (13.3%) and none ocular changes. Molecular analysis revealed eight novel private COL4A4 gene mutations: three frameshift, three missense and two splice-site mutations. Conclusions. These data indicate autosomal dominant Alport syndrome as a disease with a low risk of ocular and hearing anomalies but with a significant risk to develop renal failure although at an older age than the X-linked form. We were unable to demonstrate a genotype–phenotype correlation. Altogether, these data make difficult the differential diagnosis with the benign familial haematuria due to heterozygous mutations of COL4A4 and COL4A3, especially in young patients, and with the X-linked form of Alport syndrome in families where only females are affected. A correct diagnosis and prognosis is based on a comprehensive clinical investigation in as many family members as possible associated with a broadly formal genetic analysis of the pedigree.